Often those poppers are calibrated to higher power factor loads, using min-spec 9 just doesn't cut it.
If set up right, they should be cal'd to lighter PF. min-spec (125pf) should be plenty adequate. They have to be set awfully heavy before 125pf ammo won't do the job. (Rules say they have to be cal'd to 115-125pf, I have some 120PF I use for cal, and it's very seldom they don't take down a popper that's not malfunctioning, or you set the popper and think "wow that's really heavy").
Where min PF ammo falls on it's face is if you have low hits, edge hits, or hits not square to the face (eg depending on where you engage it from you may not be shooting it straight on). You have no margin; hotter ammo can let you get away with poorer hits and off-angle hits. again why I like to be closer to 135PF than 125PF.
IIRC 124gr NATO is typically around 145+PF.
I suspect the ammo was light. But then again, worddoer's first match was a rainy soggy mess, and it's possible the poppers took a heavy set. I didn't run cal ammo over them, but I did tap test them all during setup....
worddoer, if you want to set some aside, we can run it over a chrono.
-rvb